This invention relates to a display unit for an electronic computer, and more particularly to a display unit serving as interactive means between an operator and an electronic computer whose planar display panel can be used as a coordinate input surface.
A display unit with a data inputting function whose planar display panel can be used to input coordinates has been disclosed by Japanese Patent Application Laid-Open No. 31127/81. The conventional data input type display unit is as shown in FIG. 6.
In FIG. 6, reference numeral 400 designates a liquid crystal panel; 500, a transparent touch panel switch; and 600, a controller. FIG. 7 is a sectional view of the transparent touch panel switch 500. In FIG. 7, reference numeral 501 designates an upper transparent film substrate; 502, belt-shaped X-axis transparent electrodes laid on the upper transparent film substrate 501 in such a manner that they are in parallel with one another; 503, a lower transparent film substrate; 504, belt-shaped Y-axis transparent electrodes laid on the lower transparent film substrate 503 in such a manner that they are in parallel with one another and perpendicular to the X-axis transparent electrodes 502; and 505, a spacer in the form of a transparent sheet having holes at the intersections of the X-axis transparent electrodes 502 and the Y-axis transparent electrodes 504.
The operation of the display unit thus constructed will be described. An operation of displaying images on the liquid crystal panel 400 is carried out in the conventional manner. The transparent touch panel switch 500 operates as follows: When the operator touches the surface of the transparent touch panel switch 500 with his finger or a writing pen, the X-axis transparent electrode 502 and the Y-axis transparent electrode 504 are brought into contact with each other through the hole of the spacer 505 at the part of the surface of the panel switch 500 which has been touched by the operator. Under this condition, the controller 600 scans all the X-axis transparent electrodes 502 and all the Y-axis transparent electrodes 504 of the transparent touch panel switch 500 to detect conduction or nonconduction at the intersections of the X-axis and Y-axis transparent electrodes 502 and 504, thereby to detect the position on the surface of the liquid crystal panel 400 which has been indicated with the finger or writing pen.
The conventional display unit described above suffers from the following difficulties: The display unit is so designed that the image displayed on the liquid crystal panel is observed through the transparent touch panel, and therefore the display quality is lowered as much. This difficulty may be overcome by increasing the resolution of the transparent touch panel switch substantially to that of picture elements displayed. However, employment of the method results in increasing the manufacturing cost of the display unit, and gives rise to another problem that the transparent touch panel switch and the liquid crystal panel must be accurately aligned with each other in display dot position.